Recent years have witnessed practical use of a flat-panel display in various products and fields. This has led to a demand for a flat-panel display that is larger in size, achieves higher image quality, and consumes less power.
Under such circumstances, great attention has been drawn to an organic EL display device that (i) includes an organic electroluminescence (hereinafter abbreviated to “EL”) element which uses EL of an organic material and that (ii) is an all-solid-state flat-panel display which is excellent in, for example, low-voltage driving, high-speed response, and self-emitting.
An organic EL display device includes, for example, (i) a substrate made up of members such as a glass substrate and TFTs (thin film transistors) provided to the glass substrate and (ii) organic EL elements provided on the substrate and connected to the TFTs.
An organic EL element is a light-emitting element capable of high-luminance light emission based on low-voltage direct-current driving, and includes in its structure a first electrode, an organic EL layer, and a second electrode stacked on top of one another in that order, the first electrode being connected to a TFT. The organic EL layer between the first electrode and the second electrode is an organic layer including a stack of layers such as a hole injection layer, a hole transfer layer, an electron blocking layer, a luminous layer, a hole blocking layer, an electron transfer layer, and an electron injection layer.
A full-color organic EL display device typically includes organic EL elements of red (R), green (G), and blue (B) as sub-pixels aligned on a substrate. The full-color organic EL display device carries out an image display by, with use of TFTs, selectively causing the organic EL elements to each emit light with a desired luminance.
Such an organic EL display device is produced through a process that forms, for each organic EL element serving as a light-emitting element, a pattern of a luminous layer made of an organic luminescent material which emits light of at least the above three colors (see, for example, Patent Literatures 3 to 5).
Such formation of a luminous layer pattern is performed by a method such as (i) a vacuum vapor deposition method that uses a vapor deposition mask referred to as a shadow mask, (ii) an inkjet method, and (iii) a laser transfer method.
The production of, for example, a low-molecular organic EL display (OLED) has conventionally used a vapor deposition method involving a shadow mask, the vapor deposition method forming organic layers by discriminative application.
The vacuum vapor deposition method involving a shadow mask uses a shadow mask that is so sized as to allow vapor deposition to be performed over the entire vapor deposition region of a substrate. The vacuum vapor deposition method provides an opening in the shadow mask in the pattern of the vapor deposition region, and then fixes (for example, welds) the shadow mask to a mask frame under tension to prevent the mask from bending. The vacuum vapor deposition method next places the opening of the shadow mask in contact with a substrate at its partition wall, and causes vapor deposition particles from a vapor deposition source to be deposited (adhered) onto a desired position of the substrate through the opening of the shadow mask. This forms patterns of the luminous layer and the like.
FIG. 27 is a cross-sectional view schematically illustrating an example configuration of a conventional vapor deposition device involving the use of a shadow mask. The vacuum vapor deposition method involving a shadow mask, as illustrated in (a) of FIG. 27, forms a pattern by (i) placing a substrate 301 and a vapor deposition source 302 at such positions that the substrate 301 and the vapor deposition source 302 face each other, (ii) forming, in a shadow mask 303, openings 304 corresponding to a pattern of a portion of a target vapor deposition region so that no vapor deposition particles are adhered to a region other than the vapor deposition region, and (iii) depositing vapor deposition particles onto the substrate 301 through the openings 304.
The substrate 301 is placed in a vacuum chamber (not shown). The vapor deposition source 302 is fixed below the substrate 301. The shadow mask 303 is either fixed in close contact with the substrate 301 or moved relative to the substrate 301 while the substrate 301 and the vapor deposition source 302 are fixed to an inner wall of the vacuum chamber.
FIG. 28 is a cross-sectional view schematically illustrating another example configuration of a conventional vapor deposition device involving the use of a shadow mask. This vapor deposition device, as illustrated in FIG. 28, uses a metal mask 402 smaller in size than a substrate 401 to perform vapor deposition sequentially onto portions of the substrate 401 for formation of a pattern of a vapor deposition substance 406 throughout a surface of the substrate 401. Further, the above vapor deposition device includes a cylindrical partition wall 408 that surrounds a vapor deposition source 403 to confine the vapor deposition substance 406 from the vapor deposition source 403 in the space defined by the partition wall 408.